mod128.h

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/**********************************************************************
 * File:        mod128.h  (Formerly dir128.h)
 * Description: Header for class which implements modulo arithmetic.
 * Author:      Ray Smith
 *
 * (C) Copyright 1991, Hewlett-Packard Ltd.
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 ** http://www.apache.org/licenses/LICENSE-2.0
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 *
 **********************************************************************/
 
#ifndef MOD128_H
#define MOD128_H
 
#include "points.h"
 
namespace tesseract {
 
#define MODULUS 128   /*range of directions */
#define DIRBITS 7     // no of bits used
#define DIRSCALE 1000 // length of vector
 
class DIR128 {
public:
  DIR128() = default;
 
  DIR128(              // constructor
      int16_t value) { // value to assign
    value %= MODULUS;  // modulo arithmetic
    if (value < 0) {
      value += MODULUS; // done properly
    }
    dir = static_cast<int8_t>(value);
  }
  DIR128(const FCOORD fc); // quantize vector
 
  DIR128 &operator=(   // assign of int16_t
      int16_t value) { // value to assign
    value %= MODULUS;  // modulo arithmetic
    if (value < 0) {
      value += MODULUS; // done properly
    }
    dir = static_cast<int8_t>(value);
    return *this;
  }
  int8_t operator-(              // subtraction
      const DIR128 &minus) const // for signed result
  {
    // result
    int16_t result = dir - minus.dir;
 
    if (result > MODULUS / 2) {
      result -= MODULUS; // get in range
    } else if (result < -MODULUS / 2) {
      result += MODULUS;
    }
    return static_cast<int8_t>(result);
  }
  DIR128 operator+(            // addition
      const DIR128 &add) const // of itself
  {
    DIR128 result; // sum
 
    result = dir + add.dir; // let = do the work
    return result;
  }
  DIR128 &operator+=( // same as +
      const DIR128 &add) {
    *this = dir + add.dir; // let = do the work
    return *this;
  }
  int8_t get_dir() const { // access function
    return dir;
  }
 
  int8_t dir; // a direction
};
 
} // namespace tesseract
 
#endif